I am not sure. I also walk in to the spot I want to start in the dark. Once I am there I sit and wait to hear a bird and then decide to make another move. I have had it where I know I have walked under a turkey roosted in a tree because it gobbled right behind me on the trail i walked in.
We've become fairly convinced they can't see well even in dim light, or just don't care much about things underneath of them b/c they see/hear so many other things under them at night. Mainly believe this due to instances of getting very close, on purpose or not, and not getting busted when we were sure that we should have. I walked right past 8 the other day, and right under the gobbler, 45 mins before daylight. They pitched to the other side of the creek I was on and started strutting, and luckily it had a high bank but shallow water and I was able to slide over to their side after they hit the ground and get it done.
Same morning my brother and friend were coming in a lot closer to shooting time and found themselves right under a whole flock, literally under a few. They held still, and the whole group pitched down in front of them a few minutes later and he killed one.
Still promote being quiet, and I've busted my fair share from trees close to shooting time, but I don't believe they have the greatest low light vision.
If you silhouette yourself their low light vision doesn’t have to to great and you can easily do that 30/45 minutes before legal time just as the sun is casting a glow on the horizon. We’ve all walked under them and not had them bust. That means either they were sleeping or you just sounded like a typical noise, and didn’t walk in the open but hugged trees while you walked. My thoughts.